helmet safety?

At the LA Bike Summit, Los Angeles mayor, Antonio Villaraigosa, called for a mandatory helmet law in California. On the surface a helmet law seems like a reasonable way to improve the safety of cycling – I’m sure I’m not the only cyclists that taught a helmet equals less chance of a massive head injury – but it’s not as cut and dry.

Helmet laws have been on the books in Western Australia since 1992 and the data shows the benefits aren’t that clear and that the biggest impact helmet laws have is to discourage cycling:

Injuries to cyclists follow a clear “safety in numbers” relation; injury rates per cyclist are lower when more people cycle. Data for cyclists in collisions with motor vehicles (see bmj.com) show helmet laws increased the risk of death or serious head injury relative to the risk for pedestrians and the amount of cycling. This implies helmet laws are counterproductive.

Collisions with motor vehicles cause nearly all deaths and debilitating head injuries among cyclists. A UK emergency department study found that such collisions caused 58% of head injuries to adult cyclists and 50% of all head injuries to cyclists. The large benefits from the road safety campaigns should be contrasted with the lack of obvious effect on head injuries from helmet laws. Yet helmet laws were far more expensive. All published cost-benefit analyses of injury rates before and after helmet laws show the cost of helmets exceeded any estimated savings in healthcare costs.

In addition to those who feel that helmet laws are counterproductive when attempting to improve the overall safety of cycling, some in the “anti-helmet” camp question the safety benefits of helmets. Earlier this month an Australian woman managed to have a fine she received for not wearing a helmet overturned based on the idea that, “she would be at greater risk of brain damage from ‘diffuse external injury,’ an injury similar to shaken baby syndrome, than if she fell on her bare head.” Below is a video of Sue Abbott talking about her case:

The data on the effectiveness of helmet wearing I’ve reviewed is weak and often relies on the theory that people who wear helmets might feel safer and act more reckless. Obviously, there are certain types of accidents that will result in serious injury or death regardless of headwear, but, anecdotally, the few times I’ve crashed my bike I’ve been happy to have had a helmet on.

Should there be a mandatory helmet law? No. Should people choose to wear helmets? Probably.

It's not really about compliance. I guess I left that bit out. Compliance with the law is actually quite high (I saw one study about Australia that said something like 82%) but what happens is at least 1/3 of non-helmeted cyclists just stop riding bikes once the law goes into effect. Seatbelts are different (no additional cost). Until I started down this rabbit hole I was, at least marginally, pro helmet law but taking into consideration the deterent factor helmets can have on cycling I've changed my mind.

The other interesting thing I noted, in a couple of different studies, was the fact that, statistically speaking, you are just as likely to get a head injury walking as you are cycling (the study didn't mention the severity of head injuries or any difference between the two).